Reinforced retention structures

ABSTRACT

A medical device includes an elongated member and a reinforced retention structure. The device can be used for draining substances from organs or abscessed areas within a body of a patient. The elongated member is made of a flexible material. The reinforced retention structure extends from or is formed integrally with the elongated member and comprises an elastic member and the flexible material. The reinforced retention structure provides retention strength while providing flexibility and patient comfort. The use of the reinforced retention structure also provides increased stability to the device within the patient&#39;s body and combats migration and/or expulsion of the device. The nature of the reinforcement in the retention structure may extend into the elongated member, which allows for larger drainage openings in the device and increases the radiopacity of the device.

RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/195,995, filed Apr. 11, 2000.

TECHNICAL FIELD

[0002] This invention generally relates to medical devices, such asdrainage stents and catheters.

BACKGROUND INFORMATION

[0003] Medical devices used for draining fluids from body cavities aregenerally made of plastic tubing. The tubing is often pre-formed on oneor both of its ends to a geometry designed to maintain or anchor thedevice in position within the body. Medical devices of this type arecommonly placed through a ureteroscope, laprascope, or endoscope andinto lumens and/or body orifices. In the case of abscess catheters,placement generally occurs percutaneously through a puncture of theexternal dermis and musculature. In most cases, however, a guidewire isfirst passed through the orifice or puncture to the desired drainagesite, around or through obstacles if required. The medical device isthen placed over the guidewire through a lumen running the full lengthof the device. This straightens the anchoring geometry to ease and allowinsertion. After insertion, the guidewire is pulled out through thedevice's proximal end. Once the guidewire is removed from the body, theanchoring geometry assumes its natural, pre-formed shape to retain thedevice in position within the body of the patient.

[0004] Some medical device use coils or pigtails as anchors in an openarea of the anatomy, such as the renal pelvis of a kidney or abscessedarea within a body cavity. These types of anchors allow the device (suchas a ureteral drainage stent) to maintain its position within the bodyby blocking its migration through thinner tract openings. Another typeof anchoring mechanism is commonly known as a malecot. Some otherdevices, such as biliary stents, use one or more barbs (formed, forexample by partially skiving a tube in a longitudinal direction). Somebiliary stents use barbs for retention in the biliary tract.

SUMMARY OF THE INVENTION

[0005] Known anchoring mechanisms used with medical devices can fail.For example, internal forces from involuntary bodily functions (such asperistalsis and other secretory forces, as well as patient movement) canforce the device out of its intended position within the body. Inaddition, doctors typically recommend catheter and stent anchoring orretention structures fabricated from softer materials to enhance patientcomfort. These softer materials generally have lower retention strengthsas compared to more rigid materials. Also, the lower strengths of thesesofter materials limits the size of holes that can be formed in themedical device to help drain fluid from the body of a patient.

[0006] The present invention provides significantly increased strengthto retention structures while also maintaining patient comfort. With theinvention, softer materials can be used to maximize patient comfort, andreinforcement of these soft materials affords greater retentionproperties. Examples of devices that can include retention structuresaccording to the present invention include, but are not limited to, adrainage catheter, a ureteral stent, a urethral stent, a biliary stent,and a prostatic stent.

[0007] In general, one aspect of the present invention relates to amedical device comprising an elongated member and a reinforced retentionstructure. The elongated member comprises a flexible material anddefines a lumen extending therethrough. The reinforced retentionstructure extends from the elongated member and comprises an elasticmember and the flexible material.

[0008] The elastic member may be embedded within the flexible material,or bound to a surface of the retention structure such as the inner orouter wall of the retention structure. The retention structure mayextend from the distal or proximal portions of the device, lie betweenthe distal and proximal portions in a middle portion, or exist in or ontwo or more portions of the device.

[0009] As used herein, “distal portion” refers to the portion of themedical device furthest away from the medical operator inserting thedevice within the open or abscessed area of the anatomy, such as theportion in and/or near the kidney. “Proximal portion” refers to theopposite portion of the device closest to the medical operator, such asthe portion in and/or near the urinary bladder. “Middle portion” refersto the portion of the medical device that lies between the distal andproximal portions.

[0010] In some embodiments, at least one large drain hole slot is formedthrough the wall of the retention structure. The use of the elasticmember in the retention structure eliminates the risk that the retentionstructure will collapse on itself because of the size of the drainholes. Alternatively or additionally, the elastic member may extend intothe elongated member. Because of the stability provided by thisconfiguration, a large drain hole slot may be cut into the elongatedmember in place of typical smaller drain hole configurations. Also, theelastic member increases the radiopacity of at least the retentionstructure, thereby enhancing the locatability of the device (or at leastthe retention structure) using flouroscopy.

[0011] The extension of the elastic member into the elongated memberalso enhances pushability of the device during insertion into a body ofa patient. The elastic member prevents the device from kinking as itmoves within the body. In one embodiment, the elastic member may beremovable from the elongated member after insertion. Under thisconstruction, two separate elastic members reside in the retentionstructure and the elongated member. The length of the elastic memberdisposed in the elongated member exceeds the length of the device. Afterinsertion of the device into the body of the patient, the operatorproximally pulls the elastic member residing in the elongated memberfrom the patient's body. The elastic member residing in the retentionstructure remains in place.

[0012] The shape of the retention structure and its positioning withrespect to the elongated member can vary in different embodimentsaccording to the invention. The retention structure may be formedintegrally with the elongated member or it may be affixed to theelongated member. A retention structure may be located anywhere alongthe length of the elongated member. Also, two or more retentionstructures may be disposed along the length of the elongated member.

[0013] In one embodiment, a elastic member is pre-formed to a curvedshape and disposed within the wall of a plastic tubing. The curved shapemay be a retention structure with a single turn, a retention structurewith two or more turns, or simply a J curl. In another embodiment, aplurality of lengths of a pre-formed elastic material can be positionedlongitudinally in the wall of a piece of tubing surrounding a centrallumen. Portions of the tubing can then be cut longitudinally in betweenthe superelastic pieces to form the arms of a malecot. In anotherembodiment, a dual-lumen tube is partially skived at one end into abarbed configuration. A preformed curved piece of elastic material issecured in the skived portion for added strength.

[0014] In other embodiments, one or more elastic rings radiallyprotruding from the elongated member and containing a reinforcingsuperelastic ring and a flexible material may be formed or disposedalong the elongated member as a retention structure. By varying the sizeof the rings, the device can accommodate body cavities of differentshapes and sizes and work in maintaining the lumen of the tube wideopen. The elastic ring or rings may be constructed from a variety offlexible materials, such as elastomeric compounds. Materials like thesecombine rigidity and the softness necessary for patient stability andcomfort.

[0015] In all of the above-described embodiments, a plurality of drainholes may be cut into the elongated member and/or retention structure tomaximize drainage. Alternatively or additionally, large drain hole slotscan be cut into the elongated member and/or retention structuredepending on the placement of the elastic member.

[0016] In other aspects, the invention involves methods of placingmedical devices, such as the devices previously described. A method ofplacing a medical device of the invention into the body of a patientcomprises providing the device, collapsing the retention structure andinserting the device into a patient's body to release the retentionstructure, and thereby deploy the medical device in the body.

[0017] In another aspect, the invention involves methods of makingmedical devices of the present invention. A method of making such adevice comprises extruding an elongated member made of a flexiblematerial and incorporating a pre-formed elastic member to the flexiblematerial by embedding the elastic member within the flexible material orby binding the elastic member to a surface or groove of the flexiblematerial to form a reinforced retention structure.

[0018] The foregoing and other objects, aspects, features, andadvantages of the invention will become more apparent from the followingdescription, drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In the drawings, like reference characters generally refer to thesame parts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention.

[0020]FIG. 1. is a schematic side view of one embodiment of the medicaldevice of the invention with an elongated member and a single loopretention structure.

[0021]FIG. 1A is an enlarged cross sectional view of a cut-out portionof the single loop retention structure of FIG. 1.

[0022] FIGS. 2A-B show two side views of an insertion catheter withstylet for collapsing a single loop retention structure and insertingthe catheter into a body of a patient with the retention structuredeployed (A) and collapsed (B).

[0023] FIGS. 3A-C show transverse cross-sectional views of variousembodiments of retention structures of medical devices of the invention.

[0024] FIGS. 4A-C show additional transverse cross-sectional views ofvarious embodiments of retention structures of medical devices of theinvention.

[0025]FIG. 5 is a schematic longitudinal view of the medical device ofthe invention with an elongated member and two retention structures.

[0026]FIG. 6 is a schematic longitudinal view in partial longitudinalcross-section of a portion of an embodiment of the medical device of theinvention with an elongated member and a reinforced malecot.

[0027] FIGS. 7A-B show two side views of an insertion catheter withstylet for inserting embodiments of a medical device of the inventioninto a body of a patient with the retention structure deployed (A) andcollapsed (B).

[0028]FIG. 8 is a schematic longitudinal view in partial longitudinalcross-section of a portion of an embodiment of the medical device of theinvention with an elongated member and a reinforced barb.

[0029]FIG. 9 shows a longitudinal view of an insertion catheter withstylet and cannula for inserting an embodiment of the medical device ofthe invention into a body of a patient.

[0030]FIG. 10 is a schematic longitudinal view in partial longitudinalcross-section of one embodiment of the medical device of the inventionwith an elongated member and an inward spiral coil.

[0031]FIG. 11 is a schematic longitudinal view of a portion of anembodiment of the medical device of the invention with an elastic ringretention structure.

[0032] FIGS. 12A-B are schematic longitudinal views of a portion of twomedical devices of the invention with collapsed retention structuresillustrating a comparison of a series of holes configuration (FIG. 12A)with the reinforced large drain hole configuration of the presentinvention (FIG. 12B).

[0033]FIG. 13 is a schematic diagram illustrating the medical device ofthe invention implanted within the kidney and ureter of a patient.

DESCRIPTION

[0034] Medical devices of the present invention are generallyconstructed of an elongated member and a reinforced retention structure.The elongated member includes a flexible material and the reinforcedretention structure includes the same or a different flexible materialwith an elastic member embedded within or bound to a surface or grooveof the flexible material. Preferred materials for the flexible materialinclude, but are not limited to plastic, silicone, TEFLON®, and otherPTFE polymers, polyurethane polymers and the like. These materials mayalso be provided with radiopaque portions to assist in the implantationof the devices in a body of a patient under fluoroscopic monitoring.

[0035] The elongated member may be tubular or conical or a combinationof both. Generally, the elongated member comprises a lumen extendingthrough the entire length of the elongated member to provide drainage offluid from a body cavity. Alternatively or additionally, drainage may beprovided or enhanced by grooves located on the external surface of theretention structure and/or elongated member.

[0036] The reinforced retention structure is designed to anchor themedical device in place notwithstanding certain forces such as internalforces from involuntary bodily functions such as peristalsis and othersecretory forces, or patient movement. The reinforced retentionstructure may be formed as an extension of the elongated member. Underthis construction, an elongated member is molded into a predeterminedshape to form a reinforced retention structure such that it can extendfrom the elongated member. Alternatively, a reinforced retentionstructure may be fixedly mounted to the elongated member in that boththe elongated member and retention structures are pre-formed andthereafter attached to one another. The reinforced retention structuremay adopt any geometry that protrudes laterally or radially from theelongated member to provide adequate anchoring. Examples of retentionstructure geometry include, but are not limited to, a retention coilincluding one turn, a retention coil including two or more turns, a Jcurl, an inward spiral coil, a barb, a malecot, and a protruding ring.The retention structure and/or the elongated member itself can have anumber of drainage holes disposed along its length. The holes providedrainage areas to allow fluids to drain into the lumen of the elongatedmember. Alternatively or additionally, a large drain hole slot (FIG.12b) may be cut into the retention structure and/or the elongated memberto further facilitate drainage.

[0037] Retention structures according to the invention may be reinforcedby a segment made of an elastic member embedded within the flexiblematerial or bound to a surface or groove of the retention structure(such as the inner or outer wall of the retention structure). Theelastic member may have a cross-section that can be round, flat, square,crescent or D-shaped. Certain examples of these cross-sectional shapesare illustrated in FIGS. 3A-C and 4A-C.

[0038] The elastic member may be fabricated from a material having“superelastic” properties. Materials with superelastic properties, makeit possible to configure a segment into a particular advantageous shapeof a retention structure, such as a pigtail, a malecot arm, a coil, abarb or a ring and then modify reversibly the geometry of the retentionstructure by straightening the retention structure through use ofguidewires, outer sheaths and the like for easy implantation in thebody. For example, the pigtail, malecot, and coil retention structuresassume straightened geometries when placed over or within the length ofa cannula. After the device is straightened, placement into a body withconventional insertion techniques may occur. After insertion and removalof the straightening device, the elastic member reverts spontaneously toits predetermined configuration thereby regaining its deployed geometryand reforming the retention structure.

[0039] The superelastic material may comprise an alloy of In—Ti, Fe—Mn,Ni—Ti, Ag—Cd, Au—Cd, Au—Cu, Cu—Al—Ni, Cu—Au—Zn, Cu—Zn, Cu—Zn—Al,Cu—Zn—Sn, Cu—Zn—Xe, Fe₃Be, Fe₃Pt, Ni—Ti—V, Fe—Ni—Ti—Co, and Cu—Sn.Preferably, the superelastic material comprises a nickel and titaniumalloy, known commonly as Nitinol available from Memry Corp ofBrookfield, Conn. or SMA Inc. of San Jose, Calif. The ratio of nickeland titanium in Nitinol may be varied. Examples include a ratio of about50% to about 52% nickel by weight or a ratio of about 47% to about 49%nickel by weight. Nitinol has shape retention properties in itssuperelastic phase.

[0040] In other embodiments, the elastic member comprises any suitablematerial that has sufficient elastic properties to allow forstraightening of the retention structure during insertion into the body,but provides desired reinforcement strength to the retention structureduring use. Such materials include, for example, stainless steel orsuitable polymeric materials.

[0041] The elastic member disposed within the retention structure mayhave a one-dimensional shape, such as a linear wire, a two-dimensionalshape, such as a curled wire to form a loop or an inward coil, or athree-dimensional shape, such as a helical coil or a pigtail coil. Intwo-dimensional embodiments, the wire may be bent along a second axissuch that the wire occupies a plane. In three-dimensional embodiments,the wire may be coiled tightly about itself within the retentionstructure.

[0042] An embodiment of a medical device 10 according to the presentinvention is shown in FIG. 1. The medical device comprises an elongatedmember 12 and a reinforced retention structure 14. The elongated membermay be viewed as extending along a first axis 16. In FIG. 1 the firstaxis 16 extends in a longitudinal direction. The retention structure 14extends along the first axis 16 and a second axis 18. As seen in FIG. 1,the second axis 18 extends laterally from the first axis 16. Theelongated member 12 defines an internal lumen 20. The internal lumen 20also extends into and through the retention structure 14.

[0043] In FIG. 1, the retention structure 14 is shaped into a coilincluding a single turn. The retention structure comprises a reinforcingstructure made of an elastic member 22 embedded within a flexiblematerial 24. FIG 1A is an enlarged cross sectional view of an portion ofthe single loop retention structure of FIG. 1, and depicts the elasticmember embedded within the flexible material. Alternatively, thereinforcing elastic member 22 may be bound to an inner or outer wall ofthe flexible material 24. The stability provided by the elastic member22 to the retention structure 14 allows for a large drain hole slot 26to be cut into the retention structure 14 alongside the reinforcingmaterial 22. Optionally, the elastic member 22 can extend into theelongated member 12. A large drain hole slot 28 may be cut into aportion of a wall of the elongated member 12 for increased drainage. Tofacilitate drainage, both the retention structure 14 and/or theelongated member 12 may, alternatively or additionally, incorporate aplurality of drainage holes 30 disposed along their lengths to permitdrainage of fluid into the lumen 20.

[0044] Insertion of the device 10 into a body of a patient can beaccomplished by straightening the retention structure 14 with a rigidelongated member along the first axis 16, such as inserting a stylet orguidewire within the lumen 20 or a cannula or sheath over the elongatedmember, inserting the device 10 with the rigid member into the body andremoving the rigid member from the device to deploy the retentionstructure once the device has been inserted and properly positionedwithin a body cavity. Removal of the rigid member from the device 10releases the constraint on the elastic member and allows the retentionstructure to regain its shape. For example, referring to FIGS. 2A-B, acatheter includes a rigid member 13 connected to a handle 17 manuallyinserted into the lumen of the device 10. The catheter 15 comprises anadapter 19 for attaching the medical device 10 to the handle 17, anothercatheter, or a collection bag. When the rigid member 13 extendsthroughout the entire device 10 as in FIG. 2B, the single coil retentionstructure 14 is straightened along the longitudinal axis 16. Theinsertion catheter 15 is then inserted into a body of a patient, and therigid member 13 is removed from the body proximally. The elastic memberallows the retention structure 14 to regain its coiled shape in the bodyupon removal of the rigid member 13 as in FIG. 2A.

[0045] The elastic member may have a variety of shapes and arrangementswithin the wall of the flexible material 24 forming the retentionstructure. For example, FIGS. 3A-C represent cross-sectional views ofretention structures 14 of the present invention, and show a wire madeof a elastic core 22 disposed within the wall of the retention structure14. This configuration and these shapes may be suitable for coiledreinforced retention structures (e.g. FIGS. 1, 5, and 10) or barbedretention structures (e.g. FIG. 8). In cross-section, the inner lumen 20is surrounded by the walls of the retention structure 14 with theelastic member 22 embedded within the flexible material 24. The elasticmember 22 embedded within the flexible material 24 may be D-shaped asshown in FIG. 3A, round as in FIG. 3B, or flat, rectangular, orribbonlike as in FIG. 3C. The elastic member may also have more complexshapes such as wires with enlarged or thinner segments along theirlength, or more intricate shapes such as an arrow head for a barb or thelike.

[0046] Alternatively, the retention structure may have more than oneelastic core disposed at various intervals (regular or irregular) withinthe wall of the flexible material. For example, FIGS. 4A-C show foursuperelastic cores 22 having various shapes disposed within the wall ofthe retention structure 14. In cross-section, within the retentionstructure 14, an inner lumen 20, is surrounded by the flexible material24. Elastic member 22 is disposed within the flexible material 24 of theretention structure 14. In the cross-sectional views of the embodimentsdisplayed in FIGS. 4A-C, the elastic member 22 is disposed at fourdifferent locations within the flexible material 24. These fourlocations lie at 0°, 90°, 180°, and 270° angles along the radius of theretention structure 14. The elastic member may, however, lie at anycombination of angles along the radius of the retention structure 14.These configurations may be suitable to a coil (e.g. FIGS. 1, 5, and 10)multiple barbs (e.g. FIG. 8) or multiple arms of a malecot retentionstructure (e.g. FIG. 6). The elastic member 22 within the flexiblematerial 24 may be D-shaped as in FIG. 4A, round as in FIG. 4B, or flat,rectangular, or ribbonlike as in FIG. 4C.

[0047] Referring now to FIG. 5, another embodiment of a medical device10A according to the invention is shown. The device 10A is suitable foruse as a ureteral stent, and is made of a flexible material forming anelongated member 12A. The elongated member 12A extends along alongitudinal axis 16A and forms two retention structures 32 and 34 atits proximal and distal ends defining a longitudinal portion 11therebetween. The retention structures extend along lateral axes 18A and18A′ relative to the longitudinal axis 16A. Here, both retentionstructures 32 and 34 occupy the same plane. But the retention structures32 and 34 may occupy different planes. The use of dual retentionstructures provides increased stability to the device within a patient'sbody and combats migration and/or expulsion of the device 10A. The twoor more retention structures 32 and 34 may also be positioned anywherealong the length of the elongated member 12A. The elastic member 22Aembedded within the flexible material 24A may be positioned in one orboth of these retention structures 32 and 34 and may extend along ashort segment of the wall in the longitudinal portion 11.

[0048] The enhanced stability provided to the device 10A by the elasticmember 22A in the flexible material 24A allows for a large drain holeslot 26A or slots to be cut into the side of one or both of theretention structures 32 and 34. Alternatively or additionally, a largedrain hole slot 28A may be cut into the side of the longitudinal portionof the elongated member 12A that contains the extension of the elasticmember 22A in the flexible material 24A. A plurality of drain holes 30Amay be disposed along the elongated member 12A and/or the retentionstructures 32 and 34 to permit drainage of fluid into the lumen.

[0049]FIG. 6 depicts a retention structure 35, known as a malecot, withtwo or more laterally bulging arms formed along a portion of a length ofan elongated member 12B. The elongated member 12B extends along alongitudinal axis 16B. Two arms 33 and 36 of the retention structure 35extend along a lateral axis 18B relative to the longitudinal axis 16B.The malecot 35 may also comprise a plurality of collapsible bulging armsincluding, but not limited to, any number of arms from two arms to eightarms, for example, with three to six arms typical. As with otherretention structure constructions, the malecot 35 comprises an elasticmember 22B embedded within the flexible material 24B in each of themalecot's arms. In their deployed shape, the arms may have a symmetricalomega (Ω) shape or an omega shape tilted proximally or distally as shownin FIG. 6.

[0050] Formation of the malecot 35 can be a multi-step process. A pieceof tubing may be first extruded, molded or otherwise shaped into anelongated member 12B to have a central lumen 20B surrounded by a seriesof smaller outer lumens disposed into the wall of the elongated member12B and surrounding the lumen 20B. Lengths of elastic material areshaped into curved geometries formed by a sequence of alternating convexand concave curves of varied length and radii that shape the arms of themalecot. These preformed lengths of elastic material 22B are then placedinto the outer lumens of the flexible material 24B. The multi-lumentubing is then cut longitudinally between each of the pieces of elasticmaterial 22B to separate the arms of the malecot from each other.

[0051] The elastic member 22B allows the arms of the malecot 35 toprotrude laterally from the elongated member 12B in a natural state, andcollapse to lie flat along the length of the elongated member 12B forinsertion of the device 10B as seen in FIGS. 7A-B. An insertion catheter21 comprising a rotatable handle 23 having internal threads, a threadedelement 25 that interlocks with the rotatable handle 23, a molded hub27, a rigid member 29, and a malecot in an expanded state is shown inFIG. 7A. To collapse the malecot 35, the device 10B is disposed on therigid member 29 while holding the molded hub 27 steady. Longitudinaltension exerted on device 10B by opposing tugs exerted on the hub 27 anddistal end of the rigid member 29 pulls opposite ends of the device 10Bapart and collapses the malecot 35. FIG. 7B shows the malecot 35 in itscollapsed state.

[0052] After the malecot has been collapsed, the insertion catheter 21may be directly inserted into a body of a patient. The rigid member 29is released from the device 10B by rotating the handle 23 to release itfrom the hub 27. Removal of the rigid member 29 releases tension on thedevice 10B and allows the elastic member to resume its expanded shapedeploying the malecot and securing the device 10B within the body.

[0053]FIG. 8 depicts a retention structure 38 as a barb having two ends.One end 37 of the barb is formed integrally with the elongated member12C. The other end 39 of the barb extends laterally from the elongatedmember 12C. The elongated member 12C extends along a longitudinal axis16C. The retention structure 38 extends along a lateral axis 18Crelative to the longitudinal axis 16C. The barb 38 may be disposedanywhere along the length of the elongated member 12C. The barbcomprises a curved elastic member 22C embedded within a flexiblematerial 24C. The barb 38 may or may not create an opening in theelongated member 12C depending on the depth of the cut made in theelongated member 12C. In the embodiment depicted in FIG. 6, the barbedportion 38 forms an opening 40.

[0054] To form the barbed retention structure 38 a piece of tubing isextruded to have a central lumen surrounded by a smaller outer lumen ina wall of the elongated member 12C. Two angled cuts are made into thewall of the elongated member 12C intersecting to form end 39. The end 39of the barb extending laterally from the elongated member 12C exposesthe small lumen. An elastic member 22C is shaped into a curved geometrythat will form to the shape of the barb 38. The curved length of elasticmember is then inserted into the small lumen through end 39.

[0055] Referring to FIG. 9, insertion of the device 10C into a body of apatient can be accomplished by placing the device 10C in a conventionaldelivery system 41 and inserting the delivery system 41 into a body of apatient. In FIG. 9, the device 10C is disposed over a rigid member 43 onthe delivery system 41. The delivery system 41 comprises a handle 45, athreaded hub 47, the rigid member 43, and an adapter 51 designed toattach the medical device 10C. When the device 10C is disposed over therigid member 43, the end 37 of the barb 38 formed integrally with theelongated member 12C is preferably inserted into the body first so thatthe barb 38 folds into the opening 40 created in the elongated member12C. For applications where end 39 of the barb is to be inserted first,a cannula 53 may be inserted over the elongated member 12C to cover andcollapse the barb 38 therein. Once the device is positioned into thebody, the cannula is withdrawn deploying the barb within a body cavitythereby anchoring the device 10C in the body.

[0056]FIG. 10 shows a reinforced inward spiral coil retention structure42. The inward spiral retention structure may be disposed at either endor at both ends of the elongated member 12D. The elongated member 12Dextends along a longitudinal axis 16D. The spiral coil 42 extends alonga lateral axis 18D relative to the longitudinal axis 16D. The spiralcoil 42 anchors the medical device 10D in place to prevent migration. Aswith the single and double retention coils (FIGS. 1 and 5), the elasticmember 22D embedded within the flexible material 24D in the spiral coilretention structure 42 may be disposed along its inner perimeter.Alternatively, the elastic member may be disposed along the outerperimeter of the coil or along its flanks. It may optionally also extendwithin a portion of the elongated member 12D itself. The lumen 20Dextends through at least a portion of the spiral coil 42 to facilitatedrainage of fluid and other substances and may extend all the waythrough the spiral coil 42. The elongated member 12D and the retentionstructure 42 may incorporate a plurality of holes 30D and/or a largedrain hole slot 28D to further facilitate drainage. Insertion of thedevice 10D into a body of a patient can be accomplished through use ofthe insertion catheter shown in FIG. 2.

[0057] To form a J curl retention structure, a single cut betweenapproximately ⅜ and ¾ of a turn along the spiral coil retentionstructure may be made. As shown in FIG. 10, two examples of suitablecuts 55 and 56 made in the spiral coil retention structure atapproximately ⅜ and ¾ of a turn respectively form the J curl retentionstructure. After the cut is made, the open end of the retentionstructure may then be tapered on both sides to form a small opening atthe distal tip of the device.

[0058] To form the inward spiral retention structure, a dual lumenelongated member of flexible material is provided. An elastic memberpre-formed into an inward coil may be inserted into one of the lumens,and the elongated member wound about itself to form the designatedstructure. Alternatively, the pre-formed elastic member 22 may be boundto an outer wall of the flexible material 24, and the distal end of theelongated member of flexible material wound about itself.

[0059] Referring to FIG. 11, a reinforced retention structure of theinvention can be an elastic ring 44 containing an elastic member 22Eembedded within a flexible material 24E. The elongated member 12Eextends along a longitudinal axis 16E. The retention structure 44extends along a lateral axis 18E relative to the longitudinal axis 16E.The reinforced ring may be at a 90° angle transverse from thelongitudinal axis 16E or at a lesser angle designed to adapt to variousinternal body openings. The elastic ring or rings 44 protrude from theexternal surface of the elongated member 12E. The elastic rings 44 aredesigned to provide rigidity to the device and prevent migration of thedevice 10E. Drainage holes or apertures 30E are disposed along thelength of the elongated member 12E to provide for fluid communicationwith the lumen 20E and to facilitate urinary drainage.

[0060] FIGS. 12A-B show retention structures of the present invention ina straightened configuration. In FIG. 12A, a plurality of holes 46 arecut into a retention structure to increase the drainage rate of fluidpassing through the lumen 20F. In FIG. 12B, use of an elastic memberprovides stability to the retention structure 14F to support a largecontinuous drain hole slot 48 in the surface of the retention structure14F. The drain hole slot 48 may also appear in the elongated member (notshown) if the elastic member extends out of the retention structure 14Finto the elongated member. The length and width of the drain hole slotcan vary depending on the needs of the particular patient. The width ofthe drain hole slot can be very narrow to prevent tissue in-growth.

[0061] One medical device of the present invention 10G placed into abody of a patient is illustrated in FIG. 13. The medical device 10Gcomprises an elongated member made of a flexible material and areinforced retention structure 14G including an elastic member in theflexible material. The retention structure 14G featured in FIG. 13 hasthe geometry of an inward spiral coil, but other retention structuresdescribed above may also adequately be employed. The device 10G iseasily inserted into the body through the ureter 50 and into the kidney52 of the patient, as pictured herein. Insertion is accomplished in anyconventional manner, such as collapsing the retention structure of thedevice 14G using a guidewire, stylet or cannula and then inserting thedevice 10G through the urethra. After insertion and removal of thestraightening device, the retention structure 14G of the medical devicereverts to a pre-determined geometry.

[0062] A method of manufacturing the medical devices of the presentinvention (FIGS. 1, 5, 6, 8, 10, 11) comprises providing an elongatedmember made of a flexible material and affixing a elastic member to theflexible material to form a reinforced retention structure. The elasticmember is first shaped by mechanical operation at elevated temperatures,for example 500° C. The elastic member may be shaped into a curl, acoil, a malecot, a ring or a barb. Next, the elastic member may bepositioned in the flexible material in a number of ways. For example,the pre-shaped elastic member may be introduced into a lumen of amulti-lumen extrusion tube of flexible material. The elastic member maybe fed through one of the lumens of the multi-lumen extrusion by hand orby mechanical operation. The elastic member may also be molded in athermosetting material, in that the pre-shaped elastic member is placedin a mold cavity and a flexible material poured around it such that itmay ultimately bind to an external or internal surface of the flexiblematerial. Also, the elastic member may be bound to an external orinternal surface of the flexible material with glue or tape.

[0063] Variations, modifications, and other implementations of what isdescribed herein will occur to those of ordinary skill in the artwithout departing from the spirit and scope of the invention.Accordingly, the invention is to be defined not only by the precedingillustrative description.

[0064] What is claimed is:

1. A medical device, comprising: an elongated member comprising aflexible material and defining a lumen extending through the elongatedmember; and a reinforced retention structure extending from theelongated member and comprising a superelastic material and the flexiblematerial, the reinforced retention structure for holding the device inplace within a body of a patient.
 2. The medical device of claim 1wherein the superelastic material is bound to a surface of the retentionstructure.
 3. The medical device of claim 1 wherein the superelasticmaterial is embedded within the flexible material.
 4. The medical deviceof claim 1 wherein the reinforced retention structure comprises a curvedsegment of the elongated member, with the lumen of the elongated memberextending through the curved segment, the curved segment beingstraightenable when a rigid member is inserted through the lumen.
 5. Themedical device of claim 4 wherein the curved segment comprises a curl.6. The medical device of claim 4 wherein the curved segment comprises acoil.
 7. The medical device of claim 1 wherein the reinforced retentionstructure comprises a collapsible ring, with the lumen of the elongatedmember extending through the ring, the ring being collapsible when anouter sheath is disposed over the device.
 8. The medical device of claim1 wherein the elongated member comprises a distal portion, a proximalportion and a middle portion and wherein the retention structure extendsfrom at least one of the distal, middle and proximal portions.
 9. Themedical device of claim 1 further comprising a second reinforcedretention structure.
 10. The medical device of claim 1 wherein thereinforced retention structure defines at least one drain hole.
 11. Themedical device of claim 1 wherein the reinforced retention structuredefines at least one drain hole slot.
 12. The medical device of claim 1wherein the superelastic material comprises nickel and titanium.
 13. Themedical device of claim 12 wherein the nickel comprises about 50% toabout 52% by weight.
 14. The medical device of claim 12 wherein thenickel comprises about 47% to about 49% by weight.
 15. The medicaldevice of claim 1 wherein the flexible material comprises plastic. 16.The medical device of claim 1 wherein the device is selected from thegroup consisting of a drainage catheter, a ureteral stent, a urethralstent, a biliary stent, and a prostatic stent.
 17. The medical device ofclaim 1 wherein the superelastic material is a wire having a secondarytwo-dimensional structure disposed within a longitudinal plane.
 18. Themedical device of claim 17 wherein the superelastic material forms a Jcurl.
 19. The medical device of claim 1 wherein the superelasticmaterial is a wire having a secondary three-dimensional structure. 20.The medical device of claim I further comprising a second superelasticmaterial within the elongated member.
 21. The medical device of claim 20wherein the second superelastic material is removable.
 22. A medicaldevice, comprising: an elongated member comprising a flexible materialand defining a lumen extending through the elongated member; and areinforced malecot retention structure comprising at least two arms,each of the arms comprising an elastic member and the flexible materialand formed of the flexible material, the retention structure positionedalong a portion of the length of the elongated member, the reinforcedretention structure for holding the device in place within the body of apatient.
 23. The medical device of claim 22 wherein the elongated membercomprises a distal portion, a proximal portion and a middle portion andwherein the retention structure extends from at least one of the distal,middle and proximal portions.
 24. The medical device of claim 22 furthercomprising a second reinforced retention structure.
 25. The medicaldevice of claim 22 wherein the reinforced retention structure defines atleast one drain hole.
 26. The medical device of claim 22 wherein thereinforced retention structure defines at least one drain hole slot. 27.The medical device of claim 22 wherein the elastic member is selectedfrom the group consisting of a superelastic material, a polymericmaterial and stainless steel.
 28. The medical device of claim 27 whereinthe superelastic material comprises nickel and titanium.
 29. The medicaldevice of claim 28 wherein the nickel comprises about 47% to about 52%by weight.
 30. The medical device of claim 22 wherein the device isselected from the group consisting of a drainage catheter, a ureteralstent, a urethral stent, a biliary stent, and a prostatic stent.
 31. Amedical device comprising: an elongated member comprising a flexiblematerial and defining a lumen extending through the elongated member;and a reinforced barb retention structure comprising at least one barbextending from the flexible material of the elongated member, the atleast one barb comprising an elastic member and the flexible material,the reinforced retention structure for holding the device in placewithin the body of a patient.
 32. The medical device of claim 31 whereinthe elongated member comprises a distal portion, a proximal portion anda middle portion and wherein the retention structure extends from atleast one of the distal, middle and proximal portions.
 33. The medicaldevice of claim 31 further comprising a second reinforced retentionstructure.
 34. The medical device of claim 31 wherein the reinforcedretention structure defines at least one drain hole.
 35. The medicaldevice of claim 31 wherein the reinforced retention structure defines atleast one drain hole slot.
 36. The medical device of claim 31 whereinthe elastic member is selected from the group consisting of asuperelastic material, a polymeric material and stainless steel.
 37. Themedical device of claim 36 wherein the superelastic material comprisesnickel and titanium.
 38. The medical device of claim 37 wherein thenickel comprises about 47% to about 52% by weight.
 39. The medicaldevice of claim 31 wherein the device is selected from the groupconsisting of a drainage catheter, a ureteral stent, a urethral stent, abiliary stent, and a prostatic stent.
 40. The medical device of claim 31further comprising a second elastic member within the elongated member.41. The medical device of claim 40 wherein the second elastic member isremovable.
 42. A medical device, comprising: an elongated membercomprising a flexible material and defining a lumen extendingtherethrough; and a reinforced retention structure extending from theelongated member and comprising an elastic member and the flexiblematerial, the reinforced retention structure for holding the device inplace within a body of a patient.
 43. The medical device of claim 42wherein the elastic member is bound to a surface of the retentionstructure.
 44. The medical device of claim 42 wherein the elastic memberis embedded within the flexible material.
 45. The medical device ofclaim 42 wherein the reinforced retention structure comprises a curvedsegment of the elongated member, with the lumen of the elongated memberextending through the curved segment, the curved segment beingstraightenable when a rigid member is inserted through the lumen. 46.The medical device of claim 45 wherein the curved segment comprises acurl.
 47. The medical device of claim 45 wherein the curved segmentcomprises a coil.
 48. The medical device of claim 42 wherein thereinforced retention structure comprises a collapsible ring, with thelumen of the elongated member extending through the ring, the ring beingcollapsible when an outer sheath is disposed over the device.
 49. Themedical device of claim 42 wherein the elongated member comprises adistal portion, a proximal portion and a middle portion and wherein theretention structure extends from at least one of the distal, middle andproximal portions.
 50. The medical device of claim 42 further comprisinga second reinforced retention structure.
 51. The medical device of claim42 wherein the reinforced retention structure defines at least one drainhole.
 52. The medical device of claim 42 wherein the reinforcedretention structure defines at least one drain hole slot.
 53. Themedical device of claim 42 wherein the elastic member is selected fromthe group consisting of a superelastic material, a polymeric materialand stainless steel.
 54. The medical device of claim 53 wherein thesuperelastic material comprises nickel and titanium.
 55. The medicaldevice of claim 54 wherein the nickel comprises about 50% to about 52%by weight.
 56. The medical device of claim 54 wherein the nickelcomprises about 47% to about 49% by weight.
 57. The medical device ofclaim 42 wherein the flexible material comprises plastic.
 58. Themedical device of claim 42 wherein the device is selected from the groupconsisting of a drainage catheter, a ureteral stent, a urethral stent, abiliary stent, and a prostatic stent.
 59. The medical device of claim 42wherein the elastic member is a wire having a secondary two-dimensionalstructure disposed within a longitudinal plane.
 60. The medical deviceof claim 59 wherein the elastic member material forms a J curl.
 61. Themedical device of claim 42 , wherein the elastic member is a wire havinga secondary three-dimensional structure.
 62. The medical device of claim42 further comprising a second elastic member within the elongatedmember.
 63. The medical device of claim 62 wherein the second elasticmember is removable.
 64. A method of placing a medical device within abody of a patient, comprising: providing a medical device comprising anelongated member comprising a flexible material defining a lumenextending through the elongated member and a reinforced retentionstructure extending from the elongated member, the reinforced retentionstructure comprising a superelastic material and the flexible material,the reinforced retention structure for holding the device in placewithin the body of the patient; and inserting the medical device intothe body of the patient.
 65. A method of making a medical devicecomprising: extruding an elongated member comprising a flexiblematerial; and positioning a superelastic material to form a reinforcedretention structure comprising the superelastic and flexible materials,thereby making the medical device which comprises the elongated memberand the reinforced retention structure.